SKETCH OF 4GINA AND METHANA. 22 
ences. The rocks of the Stavro district, on account of their 
quantity and importance, will be taken as the type and described 
in detail. 
Megascopically they show a largely preponderating light 
gray groundmass with a slightly pinkish cast which is dull in 
luster but very compact and fine grained, there being no gas 
pores or vesicles. The specific gravity of the Stavro rock is 
2.508, that of Spasmeno Vouno being 2.327. The latter differs 
slightly from the former in being of a purer gray color and with 
groundmass rougher in feel and not as fine grained. 
Quite abundant phenocrysts are scattered through this 
groundmass but with no trace of arrangement in lines of flow. 
The majority of these are greenish black hornblende prisms from 
0.5-2.0 mm. long. There are also seen a few stout, black, hex- 
agonal prisms of biotite measuring 3-5 mm. each way, the inte- 
rior of these often containing minute white grains which seem to 
be plagioclase. Many plagioclase phenocrysts are also present, 
of a dull white color and showing cleavage faces and occasionally 
twinning striations. In the specimens from Spasmeno Vouno 
are seen three or four pink quartz grains about 2 mm. in diam- 
eter, not surrounded by an augite fringe. 
No segregations (‘endogenous enclosures”) were seen in the 
whole district. In one or two specimens there are yellowish 
green streaks colored by epidote and due to subaérial decomposi- 
tion, and some of the plagioclase phenocrysts are colored yellow 
from the same cause. The rocks of Spasmeno Vouno are all 
more decomposed than those of Mt. Stavro, the best specimens 
from which are quite fresh. 
The hornblende-andesites from the other localities differ 
from those just described chiefly in the greater abundance and 
larger size of the phenocrysts, among which also plagioclase is 
the most important; the groundmass resembles, as a rule, that 
of Spasmeno Vouno, being not very compact and rough in feel. 
One or two of the specimens from Mt. Chondos are decomposed 
and of a pinkish brown color. 
Under the microscope these andesites show a groundmass 
